Intermetallic compound identification and Kirkendall void formation in eutectic SnIn/Cu solder joint during solid-state aging

Microstructural investigations were performed on the interfacial reactions between eutectic SnIn solder and Cu substrate during reflowing at 433?K and solid-state aging at 373?K. Cu₂(In,Sn) was identified as the only intermetallic compound (IMC) at the interface, which consists of two sublayers with different morphology, a fine-grained sublayer at the Cu side and a coarse-grained sublayer at the solder side. During solid-state aging, voids were found between these two Cu₂(In,Sn) sublayers but not at the substrate interface, which is also attributed to the Kirkendall effect considering the different diffusion fluxes of Sn or In and Cu atoms in different sublayers.     

Scale-dependent fracture mode in Cu–Ni laminate composites

Fracture behavior of Cu–Ni laminate composites has been investigated by tensile testing. It was found that as the individual layer thickness decreases from 100 to 20 nm, the resultant fracture angle of the Cu–Ni laminate changes from 72° to 50°. Cross-sectional observations reveal that the fracture of the Ni layers transforms from opening to shear mode as the layer thickness decreases while that of the Cu layers keeps shear mode. Competition mechanisms were proposed to understand the variation in fracture mode of the metallic laminate composites associated with length scale.     

Retention and thermal desorption of helium in amorphous and crystalline FeBSi alloys

Helium retention in metals is related to their atomic structure and the type of defects they contain. In order to investigate the dependence of helium retention on structure, amorphous Fe₇₉B₁₆Si₅ and crystalline FeBSi alloys were irradiated by helium ions at room temperature. In the crystalline alloy irradiated with 5 keV He⁺ ions, three types of helium trapping sites were found: surface defects produced by the irradiation, interstitial-type dislocation loops, and voids. Although these defects did not exist in the amorphous FeBSi alloy, we did observe thermal desorption peaks related to all three types. In addition, helium was released during the crystallization of amorphous FeBSi that had been irradiated by He⁺ ions.     

Tensile deformation behaviour of Zr-based glassy alloys

This paper presents a study of the deformation behaviour of a glassy phase in two Zr-based alloys, Zr₆₅Ni₁₀Cu₅Al_7.5Pd_12.5 and Zr₆₅Al_7.5Ni₁₀Pd_17.5, performed in situ in a transmission electron microscope. In contrast to the case of shear localisation and formation of 10–20 nm thick shear bands in deformed bulk glassy samples studied earlier, it is found that in thin (electron-transparent) samples the glassy phase in front of a crack deforms more homogeneously and no nanocrystallisation takes place. The reasons for such behaviour are discussed. According to the observed results, one can conclude that the studied metallic glasses can be intrinsically ductile in submicrometre-sized volumes.     

Stair-rod dislocations in perovskite films on LaAlO3 substrates

Two types of stair-rod dislocation formed at junctions of {111} stacking faults in SrTiO₃-SrRuO₃ two-layer films on LaAlO₃ substrates have been studied by high-resolution transmission electron microscopy. The first type, formed by the interaction of two stacking faults situated at the flat SrRuO₃-LaAlO₃ interface without any step, has a Burgers vector (a/3)<110>. The other type, formed by the interaction of two stacking faults, of which one starts from the SrRuO₃-LaAlO₃interface area involving an interface step, has a Burgers vector (a/3)<120>. The formation mechanism of the stair-rod dislocations and the effect of the step are discussed.     

Standing Out From the Crowd: How Comparison to Prototypes Can Decrease Health-Risk Behavior in Young Adults

This research tested whether social comparison can encourage adolescents to make less risky health decisions. Two studies demonstrated that when young adults compare themselves with drinkers, they become less willing to drink if they perceive dissimilarity between themselves and those drinkers. When participants in Study 1 compared with someone who drinks regularly, their perceived similarity to prototypical drinkers was positively related to their willingness to drink. In Study 2, participants identified or contrasted themselves with prototypical drinkers; those encouraged to contrast who also felt less similar to the prototype reported less willingness to drink. These studies support the prototype/willingness model's assumption that prototypes affect willingness to drink through social comparison.     

多层多项Logit模型：原理与应用

常用的多层线性模型要求因变量是服从正态分布的连续变量,却无法处理因变量为离散变量的嵌套数据.多层多项Logit模型能够处理因变量是无序多分类的多层嵌套数据,但这一模型在我国心理学研究中却鲜有介绍和应用.研究简要介绍了多层多项Logit模型的原理、参数估计和假设检验,然后分别用该模型和传统Logistic回归模型探讨个体因素和区域因素对35721名学生进入不同高校就读机会的影响并对结果进行了解释,结果表明多层多项Logit模型比传统Logistic回归模型更拟合数据.     

决策的三参照点理论:从原理到应用

三参照点理论(Tri-Reference Point Theory,Wang,2008a; Wang& Johnson,2012)以底线、现状和目标为参照点,将决策结果空间划分为失败、损失、获益和成功4个功能区域.根据3个参照点的心理权重的排序:底线＞目标＞现状,该模型继而推导出跨越不同区域的以现状为分界的双S-型的价值函数,以及据此产生的对于跨越不同参照点的预期结果的偏好转换、和损失-获益及失败-成功的两种不对称性.总之,风险决策的基本任务在于,在使得达到目标的可能性最大化的同时使底线不保的可能性最小化.三参照点理论将统计学和金融学中的均值与方差(均差)分析与行为决策研究中的参照点效应有机地结合在一起;在面对不同的风险选项时,通过分析各个预期结果的均差分布与3个参照点之间的关系作出适应性的决策.本文介绍了三参照点理论的基本推论、运行原则、实证检验、以及它与期望效用理论和前景理论相比较的异同之处.同时我们也探讨了三参照点理论对实践中管理决策的指导意义和多重启示.     

大学生脑科学素养现状调查

采用《大学生脑科学素养问卷》,对天津市1450名大学生脑科学素养现状进行了调查分析。结果显示:(1)大学生总体脑科学问卷正确率显著低于60%,其中,脑的功能、脑的组织结构和脑与学方面的得分更低;(2)书籍、网络和电视是大学生获取脑科学知识的重要渠道;(3)大学生对脑科学知识的总体关心程度偏低;(4)大学生脑科学素养水平受成长环境和父母文化程度因素的影响,存在年级和性别差异。